1. Field of the Invention
This invention relates to the art of marking of traffic dividing lines and other directional data on the surface or pavement on streets or highways, by applying on and securing prefabricated road marking tape material to said pavement, and of providing a marked road thereby. More particularly this invention is concerned with a new and improved advantageous method for applying road marking tape material on said pavement and with means for carrying on said method. Still more particularly, this invention relates to the art for applying prefabricated tape material to road pavements by means of a base or "primer" layer of generally thermoplastic composition compatible with that of usual road pavements and forming an intermediate layer between the marking tape and the said road pavement.
2. Description of the Prior Art
This art is a well worked one and widely known. Marking strips and equivalent signs on paved surfaces open to vehicle traffic are a traffic aid of paramount importance for traffic regulation and safety. The particular art with which this invention is concerned, is the method in which the laying down and securing on said surface a prefabricated tape of sign-forming material is generally complemented by preliminarily forming on said surface, a tape receptive layer.
A rather wide literature illustrates such art. For example, the U.S. Pat. No. 3,262,375 granted to the instant applicant (consistent with British patent specification No. 1,038,385) has taught how to form an essentially bituminous base or primer layer on the road surface for best subsequent applying of the marking tape. More recently, this art has been substantially improved as to the methods, the apparatuses and the materials made use of. Among the others, the U.S. Pat. Nos. 3,902,939, 3,964,559 and 3,964,835, all granted to the instant applicant (consistent in part with the British patent specifications Nos. 1,419,784 and 1,421,483) have taught some modified method and means for applying road marking tape material on a primer layer. The disclosures of said patents is assumed to be herein incorporated for a more exhaustive knowledge of the art and of the related patent literature as cited and made of record in said patents.
The extensive experimentation and the wide use on the roads of said sign-forming tapes have confirmed the criticality of providing a rather consistent primer layer on the road pavement as a base for the tape material. This provision has however made the road marking procedure a two-phase process including (a) the forming of the primer layer and (b) the laying of the tape material on said layer. The securing of the primer layer on the pavement, said layer being of an essentially bitumen-based thermoplastic composition, leads to pouring and doctoring on a preliminarily dried and heated road pavement a hot and fluidized composition capable of permeating the pavement pores. The laying and pressing of the tape on said layer requires that same layer has gelled or cooled down substantial solidification to resist to the pressure and to lock the sign on the road. A substantial time interval is therefore believed to be necessary between the two phases.
Additionally, the tape must be exactly applied on the preliminarily formed primer layer. Some misalignments however occur and for taking them into account the said layer must be formed at a safe extra width. This latter provision leads to extra costs and the uncovered side portions of the primer layer foul the tape applying roller means and prejudice the neatness of the sign.